MOSCOW — Russia has granted fugitive National Security Agency leaker Edward Snowden permission to remain in the country for three more years, Snowden’s attorney said Thursday, a measure that promised to further strain U.S.-Russian relations.

The decision gives the former NSA contractor the option to remain in Russia through August 2017 and, potentially, to take up Russian citizenship should he extend his stay for one year beyond that, lawyer Anatoly Kucherena told reporters.

The decision last year to grant asylum to Snowden for a year was a major factor in the souring of U.S.-Russian relations, which have deteriorated to Cold War lows over the conflict in Ukraine. The decision to extend Snowden’s stay, although not a surprise, represents another political dig by the Kremlin at the Obama administration, which made Snowden’s return to U.S. territory a high priority.

The announcement came on the day that Prime Minister Dmitry Medvedev said Russia would ban all meat, produce and milk imports from the United States, the European Union, Australia, Canada and Norway for a year.

“Starting August 1, 2014, Edward Snowden has received a residence permit for a three-year term,” Kucherena said. He said his client has not been granted official political asylum, which would allow him to stay in Russia permanently and must be decided through a separate process. Kucherena said Snowden has not decided whether to try to remain in Russia permanently.

Last year, Snowden released thousands of files about the inner workings of U.S. intelligence agencies to journalists, including those at The Washington Post and Britain’s Guardian newspaper. The subsequent articles created an uproar about the reach and extent of U.S. government surveillance both at home and abroad and led to a review by the Obama administration of intelligence agencies’ surveillance powers.

As a result of the leaks, Snowden faces U.S. charges of espionage and theft of government property, punishable by up to 30 years in prison.

Kucherena painted a picture of a somewhat lonely life for Snowden, who is working to learn Russian and rarely gives interviews.

“He has to think about his security. He has a very modest life,” Kucherena said. But Snowden is “very free” to move around, goes shopping, and visits museums and theaters, he said.

Snowden was pictured this week attending a performance at the Bolshoi Theater. In the photo released by LifeNews, a private television channel with close ties to Russian security services, Snowden was shown without his usual glasses, leaning forward and smiling, wearing a dark suit jacket and an open-collar shirt.

“He misses his relatives,” Kucherena said. “He’s away from his family, and of course it’s hard for him.

“It’s up to him whether he will stay here and apply for citizenship or go back to the United States,” the lawyer said. With the residence permit, Snowden can travel abroad for periods of up to three months, although his options are limited by the practicalities of doing so without being extradited to the United States.

Snowden spent three weeks last year in the transit zone of Moscow’s Sheremetyevo International Airport after the U.S. government revoked his passport and as Russian authorities debated what to do with him.

He is working in Russia “according to his professional background,” Kucherena said without offering details. “He is a highly qualified IT specialist.”

Snowden’s housing is not provided by the Russian government, nor does he have government protection, the lawyer said. Instead, the former contractor who fled the United States in summer 2013 survives off donations and his salary. He has guards, but they are private, Kucherena said.

The lawyer said U.S. authorities, especially from the U.S. Embassy in Moscow, had called him frequently in the months after Snowden was granted asylum last year, urging him to send Snowden back to the United States.

Michael McFaul, then the U.S. ambassador to Russia, was the main interlocutor, the lawyer said.

“I got many calls from McFaul and his advisers,” he said. “They asked me many times: ‘Please send him back to the United States.’ ”

Those calls stopped after McFaul stepped down as ambassador in February, Kucherena said, adding that he has not heard from a U.S. official since. The United States does not currently have an ambassador in Moscow, although the Senate confirmed a replacement, John Tefft, last week.